1. Field of the Invention
The invention relates to a method for manufacturing sawtooth card clothing and all-steel card clothing for processing textile fibers, in particular, in connection with a carding process. According to the method, a wire blank is provided with teeth sequentially arranged in a longitudinal direction of the wire and extending, starting at the base area, transversely to the longitudinal direction and the sawtooth wire generated accordingly is subjected, at least in the area of the teeth, to a hardening process. The invention also relates to a device for performing such a method as well as to sawtooth wire manufactured by such a method.
2. Description of the Related Art
Sawtooth wires that are manufactured by methods of the aforementioned kind from unalloyed or alloyed steels are used, for example, in cards for treating textile fibers. For this purpose, the sawtooth wires can be mounted, for example, in a coil shape on a circular cylinder support (tambour) of the card.
In modern cards, sawtooth wire having a length of several kilometers is required for producing the sawtooth card clothing or all-steel (metal) card clothing for the tambour of a card. For processing textile fibers, the tambour of the card with the wire card clothing disposed thereon is rotated about its cylinder axis so that the card clothing can pass through and clean fiber material supplied to the tambour; the tambour card clothing cooperates with stationary or oppositely driven flat cards each provided with an appropriate flat card clothing. In this type of fiber processing, for obtaining a satisfactory carding result and for preventing damage to the card it must be ensured that the sawtooth wires are mounted with high precision in such a way on the circular cylinder support that no changes of the radial spacing of the sawtooth wire tips from the axis of rotation of the tambour will result that would negatively affect the carding result or the operating reliability; even local imprecisions resulting during mounting of the wire on the tambour can cause damage of the thus formed sawtooth card clothing and all-steel card clothing that may require a complete exchange.
This is very cost-intensive in modern high-performance cards with regard to the downtimes of the machine and the required materials. Moreover, in the context of ensuring a satisfactory carding quality a random axial displacement of sequentially arranged windings must be prevented also. Moreover, for obtaining a satisfactory service life of a card, it must be ensured that an excessive wear of the sawtooth wires is prevented. For this purpose, the teeth of the sawtooth wires to be mounted on the tambour are subjected to a hardening process. For example, they can be heated by means of an open flame to their austenization temperature, respectively, and can be subsequently quenched.
In particular when heating the wire a scale or oxide layer of varying thickness can form on the wire. Such a layer presents a particular problem in regard to the required precision of the card clothing mounted in a coil shape on the support. The sawtooth wire is mounted on the rotating support by means of a wire mounting device. For ensuring the required wire mounting precision, the wire must pass through narrow guides. During this process, as a result of bending and friction of the wire in the guides, scale particles can chip off the wire surface and deposit in the mounting device and especially in the guides. Such contamination of the guides can greatly affect the wire mounting quality and the speed at which wire mounting is carried out. Moreover, because of the scale particles chipping off, it can be required to frequently interrupt the wire mounting process in order to clean the wire mounting device and, in particular, its guides. If these cleaning interruptions are not performed timely, the pulling forces acting on the wire that increase because of increasing contamination of the guides can rise to such an extent that the wire will break
In regard to these problems it has been proposed already to remove after the hardening process the scale or oxide layers produced during hardening. For this purpose, abrasive methods are known, for example, in which the wires after the hardening process are brushed with rotating metal brushes so that the adhering scale is removed as much as possible. In another method, the wire is ground by profiled grinding wheels for removing the scale layer. Finally, chemical methods are also known for removing the scale layer chemically.
However, the methods for removing the scale layer that have been proposed in view of the above mentioned problems have the disadvantage that as a result of the mechanical or chemical material removal the wire itself is also damaged to a greater or lesser degree. Moreover, the removal of the scale layer done to avoid the problems in regard to mounting the wire can also lead to the flanks and tips of the teeth of the sawtooth wire to become rounded so that the teeth lose some of the desired sharpness.